Revert "RustWrapper: add missing include"

This reverts commit 185e3b9.

Author: matthiaskrgr

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -9,7 +9,6 @@
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/ObjectFile.h"
-#include "llvm/Pass.h"
 #include "llvm/Bitcode/BitcodeWriterPass.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/ADT/Optional.h"